deep learning for medical image processing: overview

31
DRO Deakin Research Online, Deakin University’s Research Repository Deakin University CRICOS Provider Code: 00113B Deep learning for medical image processing: overview, challenges and the future Citation of the final article: Razzak, Muhammad Imran, Naz, Saeeda and Zaib, Ahmad 2018, Deep learning for medical image processing: overview, challenges and the future. In Dey, Nilanjan, Ashour, Amira S. and Borra, Surekha (ed), Classification in BioApps: Automation of Decision Making, Springer, Cham, Switzerland, pp.323-350. Published in its final form at https://doi.org/10.1007/978-3-319-65981-7_12. This is the accepted manuscript. © 2018, Springer International Publishing AG Reprinted with permission. Downloaded from DRO: http://hdl.handle.net/10536/DRO/DU:30132524

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DRO Deakin Research Online, Deakin University’s Research Repository Deakin University CRICOS Provider Code: 00113B

Deep learning for medical image processing: overview, challenges and the future

Citation of the final article: Razzak, Muhammad Imran, Naz, Saeeda and Zaib, Ahmad 2018, Deep learning for medical image processing: overview, challenges and the future. In Dey, Nilanjan, Ashour, Amira S. and Borra, Surekha (ed), Classification in BioApps: Automation of Decision Making, Springer, Cham, Switzerland, pp.323-350.

Published in its final form at https://doi.org/10.1007/978-3-319-65981-7_12.

This is the accepted manuscript.

© 2018, Springer International Publishing AG

Reprinted with permission.

Downloaded from DRO: http://hdl.handle.net/10536/DRO/DU:30132524

Deep Learning for Medical Image Processing: Overview, Challenges and Future Muhammad Imran Razzak, Saeeda Naz and Ahmad Zaib

Abstract :

Healthcare sector is totally different from other industry. It is on high

priority sector and people expect highest level of care and services

regardless of cost. It did not achieve social expectation even though it

consume huge percentage of budget. Mostly the interpretations of medical

data is being done by medical expert. In terms of image interpretation by

human expert, it is quite limited due to its subjectivity, complexity of the

image, extensive variations exist across different interpreters, and fatigue.

After the success of deep learning in other real world application, it is also

providing exciting solutions with good accuracy for medical imaging and is

seen as a key method for future applications in health secotr. In this

chapter, we discussed state of the art deep learning architecture and its

optimization used for medical image segmentation and classification. In

the last section, we have discussed the challenges deep learning based

methods for medical imaging and open research issue. 1 Introduction

Gone are the days, when health-care data was small. Due to the tremendous

advancement in image acquisition devices, the data is quite large (moving to

big data), that makes it challenging and interesting for image analysis. This

rapid growth in medical images and modalities requires extensive and M.I. Razzak CPHHI, KSAU-HS, Riyadh e-mail: [email protected] Saeeda Naz GGPGC1, Abbottabad e-mail: [email protected] Ahmad Zaib Women Medical College, Abbottabad e-mail: [email protected]

1

2 Muhammad Imran Razzak, Saeeda Naz and Ahmad Zaib

tedious efforts by medical expert that is subjective, prone to human error and

may have large variations across different expert. Alternative solution is using

machine learning techniques to automate diagnosis process however,

traditional machine learning methods are not sufficient to deal with com-plex

problem. Happy marriage of high performance computing with machine

learning promise the capacity to deal big medical image data for accurate and

efficient diagnosis. Deep learning will not only help to not only help to select

and extract features but also construct new ones, furthermore, it does not only

diagnose the disease but also measure predictive target and provides

actionable prediction models to help physician efficiently. Machine Learning (ML) and Artificial Intelligence (AI) have progressed

rapidly in recent years. Techniques of ML and AI have played important role in

medical field like medical image processing, computer-aided diagnosis, image

interpretation, image fusion, image registration, image segmentation, ˙

image-guided therapy, image retrieval and analysis Techniques of ML extract

information from the images and represents information effectively and effi-

ciently. The ML and AI facilitate and assist doctors that they can diagnose and

predict accurate and faster the risk of diseases and prevent them in time.

These techniques enhance the abilities of doctors and researchers to under-

stand that how to analyze the generic variations which will lead to disease.

These techniques composed of conventional algorithms without learning like

Support Vector Machine (SVM), Neural Network (NN), KNN etc. and deep

learning algorithms such as Convolutional Neural Network (CNN), Recur-rent

neural Network (RNN), Long Short term Memory (LSTM), Extreme Learning

Model (ELM), Generative Adversarial Networks (GANs) etc. For-mer

algorithms are limited in processing the natural images in their raw form, time

consuming, based on expert knowledge and requires a lot time for tuning the

features. The later algorithms are fed with raw data, automatic features learner

and fast. These algorithms try to learn multiple levels of abstraction,

representation and information automatically from large set of images that

exhibit the desired behavior of data. Although automated detec-tion of

diseases based on conventional methods in medical imaging has been shown

significant accuracies around for decades, but new advances in machine

learning techniques have ignited a boom in the deep learning. Deep learning

based algorithms showed promising performance as well speed in different do-

mains like speech recognition, text recognition, lips reading, computer-aided

diagnosis, face recognition, drug discovery.

The motivation of this chapter is to provide the comprehensive review of deep learning based algorithms in medical image analysis problems in terms of current work and future direction. This chapter provides the fundamental knowledge and the state of the art approaches about deep learning in the domain of medical image processing and analysis.

Deep Learning for Medical Imaging 3

2 Why Deep Learning Over Machine Learning

Accurate diagnoses of disease depends upon image acquisition and

image interpretation. Image acquisition devices has improved substantially

over the recent few years i.e. currently we are getting radiological images

((X-Ray, CT and MRI scans etc.) with much higher resolution. However,

we just started to get benefits for automated image interpretation. One of

the best machine learning application is computer vision, though traditional

machine learning algorithms for image interpretation rely heavily on expert

crafted features i.e. lungs tumor detection requires structure features to be

extracted. Due to the extensive variation from patient to patient data,

traditional learning methods are not reliable. Machine learning has evolved

over the last few years by its ability to shift through complex and big data. Now deep learning has got great interest in each and every field and es-

pecially in medical image analysis and it is expected that it will hold $300

million medical imaging market by 2021. Thus, by 2021, it alone will get more

more investment for medical imaging than the entire analysis industry spent in

2016. It is the most effective and supervised machine learning approach. This

approach use models of deep neural network which is variation of Neural

Network but with large approximation to human brain using advance mech-

anism as compare to simple neural network. The term deep learning implies

the use of a deep neural network model. The basic computational unit in a

neural network is the neuron, a concept inspired by the study of the human

brain, which takes multiple signals as inputs, combines them linearly using

weights, and then passes the combined signals through nonlinear operations

to generate output signals.

2.1 Neural Network and Deep Learning Architecture

Artificial neural networks structurally and conceptually inspired by human

biological nervous system . Preceptron is one of the earliest neural network

that was based on human brain system. It consist of input layer that is di-rectly

connect to output layer and was good to classify linearly separable patterns.

To solve more complex pattern, neural network was introduced that has a

layered architecture i.e., input layer, output layer and one or more hidden

layers. Neural network consist of interconnected neurons that takes input and

perform some processing on the input data, and finally forward the current

layer output to the coming layer. The general architecture of neural network is

shown in figure 2. Each neuron in the network sums up the input data and

apply the activation function to the summed data and finally pro-vides the

output that might be propagated to the next layer. Thus adding

4 Muhammad Imran Razzak, Saeeda Naz and Ahmad Zaib

more hidden layer allows to deal with complex as hidden layer capture non-

linear relationship. These neural networks are knows as Deep Neural network.

Deep learning provides new cost effective to train DNN were slow in learning

the weights. Extra layers in DNN enable composition of features from lower

layers to the upper layer by giving the potential of modeling complex data. Deep learning is the growing trend to develop automated applications

and has been termed in 10 breakthrough technologies of 2013. Today,

several deep learning based computer vision applications are performing

even better than human i.e. identifying indicators for cancer in blood and

tumors in MRI scans. It is improvement of artificial neural network that consist of more hidden layer that permits higher level of abstraction and

improved image analysis. It becomes extensively applied method due to

its recent unparal-lelled result for several applications i.e. object detection,

speech recognition, face recognition and medical imaging.

A deep neural network hierarchically stacks multiple layers of neurons, form-

ing a hierarchical feature representation. The number of layers now extends to

over 1,000! With such a gigantic modeling capacity, a deep network can

essentially memorize all possible mappings after successful training with a

sufficiently large knowledge database and make intelligent predictions e.g.

interpolations and/or extrapolations for unseen cases. Thus, deep learning is

generating a major impact in computer vision and medical imaging. In fact,

similar impact is happening in domains like text, voice, etc. Various types of

deep learning algorithms are in use in research like convolutional neural

Fig. 1: Trends: Deep Learning vs Machine Learning vs Pattern Recognition

Deep Learning for Medical Imaging 5

networks (CNN), deep neural network (DNN), deep belief network (DBN), deep autoencodre (dA), deep Boltzmann machine (DBM), deep conventional extreme machine learning (DC-ELM) recurrent neural network (RNN) and its variant like BLSTM and MDLATM etc (as illustrated with their pros and cons in table 1. The CNN model is getting a lot interest in digital imaging processing and vision. There different types of

architectures of CNN such as, Alexnet1 (as shown in Figure 10, Lenet

2,

faster R-CNN3, googleNEt

4, ResNEt

5, VGGNet

6, ZFnet etc.

Fig. 2: Neural network architecture

1 https://github.com/BVLC/caffe/tree/master/models/bvlcalexnet

2 http://deeplearning.net/tutorial/lenet.html

3 https://github.com/ShaoqingRen/fasterr cnn

4 https://github.com/BVLC/caffe/tree/master/models/bvlcg ooglenet

5 https://github.com/gcr/torch-residual-networks

6 http://www.robots.ox.ac.uk/ vgg/research/verydeep/

6 Muhammad Imran Razzak, Saeeda Naz and Ahmad Zaib

Table 1: Comparison of different architecture of Deep learning models

Type of Network Detail of Network PROS CONS

Deep Neural There are more It is widely used the training pro-

Network than two layers. with great accuracy cess is not trivial

(DNN) which allow com- because the error

plex non-linear is propagated back

relationship.It is to the previous one

used for classifi- layers and they be-

cation as well for come very small.

regression. The ar- The learning pro-

chitecture is shown. cess of the model is

in Figure 5. also too much slow.

Convolutional This network is very good perfor- It needs a lot of la-

Neural Net- very good for 2 mance, learning of beled data for clas-

work (CNN) dimensional data. model is fast sification.

It consists of con-

volutional filters

which transform

2D into 3D. The

architecture has

shown in Figure 3

Recurrent It has the capabil- learn sequen- there many issue

Neural Net- ity of learning of se- tial events, can due to gradient

work (RNN) quences. the wights model time de- vanishing and need

are sharing across pendencies, there of big datasets

all steps and neu- are many varia-

rons tion like LSTM,

BLSTM, MDL-

STM, HLSTM.

These provide state

of the art accu-

racies in speech

recognition, charac-

ter recognition and

many other NLP

related tasks

Deep Con- For sampling of

ventional local connections,

Extreme this network uses

Learning Gaussian proba-

Machine bility function as

(DC-ELM) shown in Figure ??

Continued on next page

Deep Learning for Medical Imaging 7

Table 1 – continued from previous page

Type of Network Detail of Network PROS CONS

Deep Boltz- This model is based the top-down feed- optimization of

mann Ma- on family of Boltz- back incorporates parameters is not

chine (DBM) mann and it con- with ambiguous possible for big

sists of unidirec- data for more dataset.

tional connections robust inference

between all hidden

layers as shown in

Figure ??

Deep Belief This model has The greedy strat- The initialization Network unidirectional con- egy used in each make the training

(DBN) nection at two layer and the infer- process computa-

layers on the top ence tractable max- tionally expensive

of layers. It is used imize directly the

in both supervised likelihood

and supervised

learning in machine

learning. The hid-

den layers of each

sub-network serves

as visible layer

for the next layer.

The architecture is

shown in Figure ??

Deep Auto- It is used in un- It does not need IT needs pre- encder (dA) supervised learning labelled data. there training step. Its

and it is designed are different vari- training may suffer

mainly for extrac- ations like Sparse from vanishing.

tion and reduction Auto-encoder,

of dimensionality of De-nosing Auto-

features. The num- encoder, Conven-

ber of input is equal tional Auto-Enc for

to number of out- more robustness.

put. It is shown in

Figure 7

8 Muhammad Imran Razzak, Saeeda Naz and Ahmad Zaib

3 Deep Learning: Not-so-near Future in Medical Imaging

Deep learning technology applied to medical imaging may become the most

disruptive technology radiology has seen since the advent of digital imag-ing.

Most researchers believe that within next 15 years, deep learning based

applications will take over human and not only most of the diagnosis will be

performed by intelligent machines but will also help to predict disease,

prescribe medicine and guide in treatment. Which field in medical has rev-

olutionised Deep learning first? ophthalmology,pathology, cancer detection,

radiology or prediction and personalized medicine. Ophthalmology will be the

first field to be revolutionized in health care, however, pathology, cancer di-

agnosis have received more attention and currently we have application with

decent accuracy. Google DeepMind Health is working with National Health

Service, UK signed five year agreement to process the medical data of up to

1m patients across the trusts five hospitals. Even its early days of this project,

Deepmind already has high hopes for the proposal.

Researchers and vendors in medical sector are moving this field forward

have a bold recommendation i.e. IBM Watson recently boosted itself through

billion-dollar entry into the imaging arena by the acquisition Merge (imag-ing

and Google DeepMind Health is another big investment. Even though, huge

investment and interest, deep learning future in medical imaging is not that

near as compare to other imaging applications due to the complexities

involved in this field. The notion of applying deep learning based algorithms to

medical imaging data is a fascinating and growing research area however,

there are several barriers that slow down its progress. These challenges are

Fig. 3: Convolutional Neural Network

Deep Learning for Medical Imaging 9

Fig. 4: type of architecture of CNN:AlexNet

unavailability of dataset, privacy and legal issues, dedicated medical experts, non standard data machine learning algorithms etc.

Fig. 5: Deep Neural Network

10 Muhammad Imran Razzak, Saeeda Naz and Ahmad Zaib

Fig. 6: Deep Belief Network (BDN)

Fig. 7: Deep Autoencoder (dA)

3.1 Dataset

Deep learning requires massive amount of training dataset as classification

accuracy of deep learning classifier is largely dependent on the quality and

size of the dataset, however, unavailability of dataset is one the biggest bar-

rier in the success of deep learning in medical imaging. On the other hand,

development of large medical imaging data is quite challenging as annotation

requires extensive time from medical experts especially it requires multiple

expert opinion to overcome the human error. Furthermore, annotation may not

be possible due to unavailability of qualified expert or availability of suf-

Deep Learning for Medical Imaging 11

ficient cases are also issue in case of rare disease. Another issue major issue is unbalancing of data that is very common in health sector i.e.rare diseases, by virtue of being rare, are underrepresented in the data sets. If not accounted for properly, the class imbalance that ensues.

3.2 Privacy and Legal Issue

It is much more complicated and difficult to share the medical data as com-

pared to real world images. Data privacy is effectively both sociological as well

as technical issue, which must be addressed jointly from both perspectives.

HIPAA comes to mind when privacy is discussed in health sector. It provides

legal rights to patients regarding their personally identifiable information and

establish obligations for healthcare providers to protect and restrict its use or

disclosure. While the rise of healthcare data, data analytics researchers see

big challenges that how to anonymize patient information to prevent its use or

disclosure ? Discarding such information (social security number, medical

record number, name and age) make it complex to link the data up to unique

individual. But still, an attacker can identify somehow using association. The

other way is differential privacy which restrict the data to organization based

on requirement of data need. These privacy challenges are factors that can

lead to situations where, data analytics model likely to impact it negatively

from both legal as well as ethical perspective. The main privacy challenges

associated with healthcare data analytics, overrunning the privacy concerns of

traditional data processing, are as follows: One important issue to address that how to share sensitive data of data

while limiting disclosure and limiting its sharing by ensuring the sufficient data utility i.e. Year of birth, 3-digit Zip code, gender is unique for 0.04% of US population while Date of birth, 5-digit Zip code and gender is unique

˙

for 87% of US population The limited restriction data access, unfortunately reduce information content too that might be very important. In addition to this, we don’t have static data but its size is increasing over time thus none of the existing prevailing methods results in making data secure.

3.3 Data Interoperability and Data Standards

Data interoperability and data standards are the one of major barrier. Cur-

rently, nature of data differ from hardware to hardware thus there exist large

variation in images due to sensors and other factors. Furthermore, the breadth

of any applications medical sector requires to combine several dif-ferent

datasets for better algorithms learning and accuracy. Interoperability is

backbone to critical improvements in health sector and yet has to become

12 Muhammad Imran Razzak, Saeeda Naz and Ahmad Zaib

a reality. Similar to the concept of ATM network, Health data should be

standardized and shared between providers. To achieve interoperability

level, HIPAA, HL7, HITECH and other health standardization bodies have

defined some standards and guidelines. How an organization gets to know that if it meet interoperability and security standards. Authorized testing

and certi-fying body (ATCB) provides an independent, third party opinion

on EHR. Two types of certification (CCHIT and ARRA) are used to

evaluate the sys-tem. Review process includes standardized test scripts

and exchange test of standardized data.

3.4 Black Box and Deep Learning

Medical imaging broke paradigms when it first began more than 100 years ago

and deep learning algorithms gave new birth to medical imaging appli-cation

and open new possibilities. It solves the problems previously thought to be

unsolvable by a machine learning algorithms, however, deep learning is not

free form the problems. One of the biggest issues is so called black-box

problem, although math used to construct a neural network is straightfor-ward

but how the output was arrived is exceedingly complicated i.e. machine

learning algorithms get bunch of data as input, identify patterns and build

predictive model but understanding how the model worked is issue. The deep

learning model is offer uninterpretable and most of the researchers are using it

without know the working process that why it provides better result.

4 Deep Learning in Medical Imaging

Many image diagnosis task requires initial search to identify abnormalities,

quantify measurement and changes over time. Automated image analysis tool

based on machine learning algorithms are the key enablers to improve the

quality of image diagnosis and interpretation by facilitating through efficient

identification of finding. Deep learning is one extensively applied techniques

that provides state of the aft accuracy. It opened new doors in medical image

analysis that have not been before. Applications of deep learning in healthcare

covers a broad range of problems ranging from cancer screening and disease

monitoring to personalized treatment suggestions. Various sources of data

today - radiological imaging (X-Ray, CT and MRI scans), pathology imaging

and recently, genomic sequences have brought an immense amount of data at

the physicians disposal. However, we are still short of tools to convert all this

data to useful information. In the below discussion, we highlighted state of the

art applications of deep learning in medical image analysis. Though,

Deep Learning for Medical Imaging 13

the list is by no means complete however it provides an indication of the long-ranging deep learning impact in the medical imaging industry today.

4.1 Diabetic Retinopathy

Diabetes Mellitus (DM) is a metabolic disorder in which pancreases cannot

produce proper insulin (Type-1) or the body tissues do not response to the

insulin properly (Type-2) which results in high blood sugar. The Diabetic

Retinopathy (DR) is an eye disease due to diabetes which results in eye

blindness with the passage of time of diabetes in a person. According to [? ], almost 415 million people are suffering from diabetes in the world and

15% amongst them have high risk of vision impairment, blindness and

loss. This disease can be controlled and cure easily if it is detected on time

and at early stage by retinal screening test.

Manual process of detection of DR is difficult and time consuming process at

presence due to unavailability of equipment and expertise. As this disease

shows hardly any symptoms in early stage and a clinician needs to examine

the colored fundus image of retina which lead to delay the treatment, mis-

communication and loss of follow up. Automated detection of DR based on

deep learning models has proven their optimized and better accuracy. In this

section, we are presenting the research work using deep learning approaches.

Gulshan et al. applied Deep Convolutional Neural Network (DCNN) on Eye

Picture Archive Communication System (EyePACS-1) dataset and Messidor-2

dataset for classification and detection of moderate and worse referable [21].

The EyePACS-1 consists of approximately 10,000 retinal images and the

Messidor-2 data set consists of 1,700 images that collected from 874 patients.

The authors claimed 97.5%sensitivity and 93.4% specificity on EyePACS-1;

and 96.1% sensitivity and 93.9% specificity on Messidor-1, respectively.

Kathirvel [9] trained DCNN with dropout layer techniques and tested on

publically available datasets like kaggle fundus, DRIVE and STARE for clas-

sification of fundus. The reported accuracy is up to 94-96%. Pratt et al. [6]

employed NVIDIA CUDA DCNN library on Kaggle dataset consisting of above

80,000 digital fundus images. They also validated the network on 5,000

images. The images resized into 512x512 pixels and then sharpened. Finally,

the features vector fed to Cu-DCNN. They classified the images into 5 classes

using features like exudates, haemorrhages and micro-aneurysms and

achieve upto 95% specificity, 30% sensitivity and 75% accuracy.

Haloi [7] implemented five layers CNN with drop out mechanism for detec-tion

of early stage DR on Retinopathy Online Challenge (ROC) and Massidor

datasets and claimed t Sensitivity, Specificity, accuracy and area under the

14 Muhammad Imran Razzak, Saeeda Naz and Ahmad Zaib

curve (AUC) up to 97%, 96%, 96% and 0.988 on Maddissor dataset and

AUC up to 0.98 on ROC dataset. Alban [8] de-noised the angiograph images of EyePACS and then applied CNNs for detection of DR. They diagnosed five classes severities and provide 79% AUC and 45%

accuracy. Lim et al. [14] extracted features from identified regions using method proposed in [26] and then the features vector passed to DCNN for

classification. They realized the model on DIARETDB1 and SiDRP datasets. All above works summarized in Table tableDiabetic.

Table 2: Summary of Deep Learning (DL) for Diabetic Retinopathy (DR).

Authors Model Data set accuracy:acc or sensitiv- ity:sensi or specificity:spec

(%)

Gulshan et Deep Convolutional EyePACS-1 97.5% sensi & 93.4% spec

al. Neural Network Messidor-2 96.1% sensi & 93.9% spec

Kathirvel CNN with dropout Kaggle-fundus, 94-96%

layer DRIVE and STARE

Pratt et al. Cu-DCNN library Kaggle 75% acc

Haloi et al. Five layers CNN Massidor ROC 98% AUC 97% AUC Alban et DCNN EyePACS 45% acc

al.

Limet al. DCNN DIARETDB1 SiDRP –

4.2 Histological and Microscopical Elements Detection

Histological analysis is the study of cell, group of cells and tissues. When

different changes come at cellular and tissue level then microscopic changes,

characteristics and features can be detected through microscopic image tech-

nology and stains (colorful chemicals) [24] [30] [29]. It involves number of

steps like fixation, sectioning, staining and optical microscopic imaging.

Different skin disease especially squamus cell carcinoma, and melanoma

Other dis-eases like gastric carcinoma, gastric ephitilial metaplasia, breast

carcinoma, malaria, Intestinal parasites and TB etc. Genus plasmodiums

parasite is the main reason of Malaria. Microscopical imaging is the standard

method for de-tection of parasites in stained blood smear sample.

Mycobacteria in sputum is the main cause of Tuberculosis (TB). Smear

microscopy and fluorescent auramine-rhodamine stain or Ziehl-Neelsen (ZN)

stain are golden standanrds for detection TB.

Recently, the HistoPhenotypes dataset published [31] where DCNN classifier

applied for diagnosis nuclei of cells of colon cancer using stained histological

images. Bayramoglu and Heikkil [1] conducted two studies for detection of

Deep Learning for Medical Imaging 15

thoraco-abdominal lymph node and interstitial lung disease using transfer learning (fine tuning) approach with CNN model. Due to limited histological data in [31], features vector extracted using facial images [13] and natural images of ImageNet [11] using source CNN and then transferred to object CNN model for classification. The CNN classifier employed for grading gas-tric cancer by analyzing signet ring cells in tissues and epithelial layers of tissue. They also count the mitotic figures for breast cancer [16].

In [23], authors employ shape features like moment and morphological to

pre-dict malaria, tuberculosis and hookworm from blood, sputum and stool

sam-ples. Automatic microscopic image analysis performed using DCNN

model as a classifier and reported AUC 100% for Malaria and 99% for

tuberculosis and hookworm. DCNN also applied for diagnosis of malaria in

[23] and intestinal parasites in [20]. Fully CNN Deep learning has been

used in [36] for auto-matic cell counting. Qiu et al. also employed DCNN

for detection of leukemia in metaphase [22]. Quin et al. conducted

experiment using DCNN for detec-tion of malaria in thick blood smear,,

intestinal parasite like helminthes in stool and mycobacteria in sputum

[23]. Malaria detection is a crucial and important research area. In 2015,

438,000 people were died due to malaria according to World Health

Organization. Dong et al. developed four systems for detection infected

and non-infected cells by malaria using CNN mod-els and SVM. Three

architectures of CNN named as GoogLeNet , LeNet-5 and AlexNet used

for automatic features extraction and classification and reported 98.13%,

96.18% and 95.79% respectively. SVM based system got lowest accuracy

upto 91.66%. Summary of all above written work is given in Table 3.

Table 3: Summary of Deep Learning (DL) for Histological and Microscopical Elements Detection. Authors Model Data set accuracy:acc or sensitiv- ity:sensi or specificity:spec

(%)

Bayramoglutransfer approach ImageNet (source for –

and with CNN features) HistoPheno-

Heikkil types dataset

quinn et DCNN and shaped microscopic image 100% for Malaria; 99% for tu- al. features like moment berculosis and hookworm

and morphological

Qiu et al. DCNN – –

Dong et al. GoogLeNet , LeNet-5, 98.66%, 96.18% and 95.79% and AlexNet acc

16 Muhammad Imran Razzak, Saeeda Naz and Ahmad Zaib

4.3 Gastrointestinal (GI) Diseases Detection

Gastrointestinal (GI) consists of all organs involve in digestion of food and

absorption of nutrients and excretion of the waste products. It starts from

mouth to anus. The organs are esophagus, stomach, large intestine (colon or

large bowel) and small intestine (small bowel). The GI may also divide into

upper GI tract and lower GI tract. The upper GI tract consists of esophagus,

stomach and duodenum (part of small bowel) and lower GI tract consists of

most of small intestine (jejunam and jilium) and large intestine. The food

digestion and absorption is affected due to different ailments and diseases like

inflammation, bleeding, infections and cancer in the GI tract [23]. Ul-cers

cause bleeding in upper GI tract. Polyps, cancer or diverticulitis cause

bleeding from colon. Small intestine has diseases like Celiac, Crohn, malig-

nant and benign tumor, intestinal obstruction, duodenal ulcer, Irritable bowel

syndrome and bleeding due to abnormal blood vessels named as arteriove-

nous malformations (angiodysplasias or angioectasias).

Image processing and machine learning play vital role in diagnosing and

analyzing these diseases and help the doctors in making fast decision for treatment efficiently and accurately. Due to advancement in computer

aided diagnosis (CAD) systems, various kind of imaging tests is in practice

for digestive systems disease detection and classification. These imaging

test are Wireless Capsule endoscopy, Endoscopy and enteroscopy,

colonoscopy or sigmoidoscopy, Radioopaque dyes and X-ray studies, deep small bowel en-teroscopy, intra operative enteroscopy, Computed

tomography and magnetic resonance imaging (MRI).

Jia et al. employed DCNN for detection of bleeding in GI 10,000 Wireless

Capsule Endoscopy (WCE) images [7]. The WCE is a non-invasive image

video method for examination small bowel disease. They claimed F measure

approximately to 99Pei etal. mainly focused on evaluation of contraction fre-

quency of bowel by investigation diameter patterns and length of bowel by

measuring temporal information [19]. The authors implemented Fully Con-

volutional Networks (FCN) and stacked FCN with LSTM using small and

massive datasets. FCN-LSTM trained on small dataset consisted of 5 cine-

MRI sequences without labeling and FCN system realized on massive dataset

consisted of fifty raw cine MRI sequence with labeling Wimmer et al. learned

features from ImageNet dataset and then the learned feature vector fed to

CNN SoftMax for classification and detection of celiac disease using duode-

nums endoscopic images [33].

A popular approach of automatic feature extraction from endoscopy images

adopted using CNN [38]. Then the features vector to the SVM for classifica-

tion and detection of gastrointestinal lesions. The proposed system realized on

180 imagesfor lesions detection and 80% accuracy reported. Similarly hy-

Deep Learning for Medical Imaging 17

brid approach used by [5]. Fast features extraction using CNN architecture in [29] applied and then the extracted features passed to SVM for detection of inflammatory gastrointestinal disease in WCE videos. The experiments con-ducted on 337 annotated inflammatory images and 599 non-inflammatory images of the GI tract of KID [30]. Training set containing 200 normal and 200 abnormal while test set containing 27 normal and 27 abnormal and ob-tained overall accuracy upto 90%.

The work involved in detection of polyp in colonoscopy videos using rep-

resentation of image in three ways [32]. Number of CNN models trained on

isolated feature like texture, shape, color and temporal information in

multiple scales which enhance the accurate localization of polyp. and then

combined the results for final decision. They claimed that their polyp

dataset is the largest annotated dataset and they decrease the latency of

detection of polyps as compare with the stat of the art techniques. Ribeiro

et al. [32] also conducted three experiment using different CNN. They

applied normalization (see details in [33]). The size of dataset increased

using data augmentation by making different variations of images. They

presented another pixels and CNN based work [34] for prognosis of polyp

tumor staging using colonic mucosa as a target attribute. The work

available on GI are summarized in Table 4.

4.4 Cardiac Imaging

Deep learning has provided extremely promising result for cardiac imaging es-

pecially for Calcium score quantification. Number of diverse applications has

been developed, CT and MRI are the most used imaging modality whereas

common task for image segmentation are left ventricle. Manual identification of

CAC in cardiac CT requires substan- tial expert interaction, which makes it

time-consuming and in- feasible for large-scale or epidemiological studies. To

overcome these limitations, (semi)-automatic calcium scoring methods have

been proposed for CSCT. Recent work on Cardiac images is focusing on CT

angeographic images based CAC computation using deep conventional neural

network as shown in figure 9

4.5 Tumor Detection

When cells of any part of the body have abnormal growth and make a mass

then it is called Tumor or Neoplasm. There are two types of tumor. One is non-

cancerous (Benign tumor) and other is cancerous (Malignant tumor). Benign

tumor is not much dangerous and it is remained stick to one part of

18 Muhammad Imran Razzak, Saeeda Naz and Ahmad Zaib

Fig. 8: Microscopic blood smear images

Fig. 9: calcium score score classification from CT [34]

Deep Learning for Medical Imaging 19

the body and do not spread to other part of the body. While malignant tu-mor

is very harmful and it spread to other part of the body. When it spreads to

other part then it is difficult to treat and prognoses also become very poor.

Wang et al [8] used 482 mammographic images having ages from 32 years to

70 years. Images of 246 women affected by tumor. First the images de-noised

using median filter and then segment the breast tumor using region growth,

morphological operations and modified wavelet transformation. Then

morphological and textural features passed to extreme learning machine and

SVM for classification and detection of breast tumor. The total error rate was

84 using ELM and 96 using SVM. Authors in [35] have limited data of

malignant mass and benign solitary cysts. CNN model needs large amount of

images for better finding of cysts and mass. Therefore CNN fed by different

variations of images and reported Area under curve upto 87%.

Arevalo et al.[36] conducted experiment on a benchmark dataset having 736

mediolateral oblique and craniocaudal mammographic views from 344 can-

cerous patients. They segmented the images manually into 310 malignant and

426 benign lesions. First, the images enhanced then fed to CNN for

identification of benign and malignant lesions. They reported 82.6% AUC.

Huynh et al. [37] used CNN for features learning on breast ultrasound images

having 2393 regions of interests form 1125 patients. They perform two ex-

periments. In first experiment, SVM model classified the extracted features

into malignant, benign and cystic and got satisfactory result. In second ex-

periment, SVM classified on hand crafted features. They obtained 88% AUC

on CNN features and 85% AUC on hand crafted features. Antropova et al. [38]

investigated CNN for transfer learning of features form ImageNet dataset (non-

madical) and SVM applied on 4,096 extracted features for classification of

breast lesions as malignant and benign using 551 MRI images consisting of

194 benign and 357 malignant. AUC reported upto 85%.

SVM used for classification and CNN used for features extraction in [39]. They

obtained AUC 86% on dataset containing 219 lesions in 607 breast images. In

[40], frozen approach of transfer learning used. DCNN trained on

mammographic images with drop out and jittering approaches with 99% AUC

and then validate on DTB images with 90% AUC after transfer learn-ing. The

datasets containing 2282 digitized film and digital mammograms [41] and 324

DBT volumes [42]. Training set containing 2282 with 2461 le-sions and 230

DBT views with 228 masses. The remaining images used as independent test.

Shin et al.[43] conducted fine tuning approach of transfer learning on

ImageNet using CNN. Then CNN model applied as a classifier for detection of

lesion in thoraco-abdominal lymph node and interstitial lung disease. The

authors got sensitivity upto 83% and 85% and AUC upto 94% and 95%,

respectively. A brief summary of published work is given in Table 5.

20 Muhammad Imran Razzak, Saeeda Naz and Ahmad Zaib

4.6 Alzheimer’s and Parkinsons Diseases Detection

Parkinsons disease (PD) is a neurological disorder associated with a pro-

gressive decline in motor precision and sensor motor integration stemming

presumably from a disorder of the basal ganglia [46]. Parkinsons disease is

associated with the breaking up or the dying of dopaminergic neurons. Neu-

rological testing like MMSE [47], and UPDRS [48]) and brain scans are rou-

tinely used to determine the diagnosis of AD [49]. The scale and shift invariant

based features like shape of data, mean and standard deviation using CNN

model (LeNet-5) , carries out classification on functional MRI 4D in work of

Sarraf and Tofigh [50]. The proposed system trained on 270900 images and

validated and tested on 90300 images in fMRI. The authors obtained 96.86%

accuracy for detection of affected brains by Alzheimer disease.

Suk [51] employed Deep Boltzmann Machine (DBM) for features extrac-tion

and detection of abnormalities from 3D patch of MRI and PET images. The

results were validated on ADNI dataset [52] for alzheimers disease us-ing

dataset of PET, MRI and combination of PET and MRI and obtained

accuracies upto 92.38%, 92.20% and 95.35%. Hosseini-Asl [53] also explored

3D-CNN for diagnosis AD and extracted generic features using CADDemen-

tia MRI dataset. The authors then fine tuned three fully connected layers CNN

for classification of AD using ADNI dataset. Sarraf et al. [54] diag-nosed

Alzheimer disease in adults (above 75 years old) using fMRI and MRI images.

The authors conducted studies based on research and clinical appli-cations.

CNN model employed for detection of healthy or Alzheimers brain and report

99.9 for functional MRI data and 98.84% for MRI data, respec-tively. They

then performed classification on subject level and finally decision making

based algorithm applied. The final accuracy improved upto 97.77% and 100%

for fMRI and MRI subjects. In [55], sparse auto encoder (a neural network)

used for extraction of features and then 3D-CNN applied as a clas-sifier on

ADNI dataset consisting of neuron images. The dataset is divided into training

set (1,731 samples), validation set (306 samples) and test set (228 sample)

and achieved performance upto 95.39% for AD and 95.39%.

Liu et al. [? ] also used sparse auto encoder fro extraction generic features and then applied sofmax of CNN for classification of affected brain by Alzheimer; or, prodromal stage or mild stage of Alzheimer. They achieved accuracy upto 87.76% on binary images of MRI and PET for early stage detection of Alzheimer disease. All methods are summarized in Table 6.

Deep Learning for Medical Imaging 21

Table 4: Summary of Deep Learning (DL) for GI.

Authors Model Data set accuracy:acc or sensitiv- ity:sensi or specificity:spec

(%)

Bayramoglutransfer approach ImageNet (source for –

and with CNN features) HistoPheno-

Heikkil types dataset

quinn et DCNN and shaped microscopic image 100% for Malaria; 99% for tu- al. features like moment berculosis and hookworm

and morphological

Qiu et al. DCNN – –

Dong et al. GoogLeNet , LeNet-5, 98.66%, 96.18% and 95.79% and AlexNet acc

Table 5: Summary of Deep Learning (DL) for Tumor Detection.

Authors Model Data set accuracy:acc or sensitiv- ity:sensi or specificity:spec

(%)

Bayramoglutransfer approach ImageNet (source for –

and with CNN features) HistoPheno-

Heikkil types dataset

quinn et DCNN and shaped microscopic image 100% for Malaria; 99% for tu- al. features like moment berculosis and hookworm

and morphological

Qiu et al. DCNN – –

Dong et al. GoogLeNet , LeNet-5, 98.66%, 96.18% and 95.79% and AlexNet acc

Table 6: Summary of Deep Learning (DL) for Alzheimer Disease Detection.

Authors Model Data set accuracy:acc or sensitiv- ity:sensi or specificity:spec

(%)

Bayramoglutransfer approach ImageNet (source for –

and with CNN features) HistoPheno-

Heikkil types dataset

quinn et DCNN and shaped microscopic image 100% for Malaria; 99% for tu- al. features like moment berculosis and hookworm

and morphological

Qiu et al. DCNN – –

Dong et al. GoogLeNet , LeNet-5, 98.66%, 96.18% and 95.79% and AlexNet acc

22 Muhammad Imran Razzak, Saeeda Naz and Ahmad Zaib

Fig. 10: Lungs nodules segmentation [3]

Application Area Input Data Deep Learning Method

Cardiac CAC CT CNN [12, 34, 35]% Lungs cancer MRI CNN [25] Lungs cancer CT DNN [2, 18] Diabetic retinopathy fundus Image CNN [6, 21] Blood Analysis Microscopic CNN [24, 36] Blood Analysis Microscopic DBN [4] Blood vessel Fundus DNN [15] Blood vessel Fundus CNN [17] Brain lesion segmentation MRI CNN [3, 8, 10] Polyp Recognition Endoscopy CNN [28, 33, 37] Alzheimer’s disease PET CNN [27]

Table 7: Summary of some deep learning based medical imaging

Deep Learning for Medical Imaging 23

5 Open Research Issues and Future Directions

Three trends that drive the deep learning revolution are availability of big data,

recent deep learning algorithm modeled on the human brain and pro-cessing

power. While deep learning potential benefits are extremely significant and so

are the initial efforts and costs. Big companies like Google DeepMind, IBS

Watson, research labs along with leading hospitals and vendors are com-ing

together and working toward the optimal solution of big medical imaging.

Siemen, Philips, Hitachi and GE Healthcare etc. have already made signifi-

cant investments. Similarly research lab such as Google, IBM are also invest-

ing towards the delivery of efficient imaging applications i.e. IBM Watson is

working with more than 15 healthcare provides to learn how deep learning

could work in real world.Similary google DeepMind health is collaborating with

NHS, UK to apply deep learning on different healthcare applications ( for

example : anonymised eye scans analysis could help to find the sing of

diseases that could leads to blindness) on dataset of 1.6 million patient. GE

Healthcare partnership with Bostons Children Hospital is working to create

smart imaging technology for detecting pediatric brain disorders. Further-more,

GE Healthcare and UC San Francisco has also announced a 3-year

partnership to develop a set of algorithms to differentiate between normal

result and one that requires further attention by expert.

5.1 Requires Extensive Inter-organization Collaboration

Despite great effort done by big stakeholder and their predictions about

the growth of deep learning and medical imaging, there will be a debate on

re-placing human with machine however, deep learning has potential

benefits towards disease diagnosis and treatment. However, there are

several issues that need to be solved to make it possible earlier.

Collaboration between hospital providers, vendors and machine learning

scientists is extensively re-quired to windup this extremely beneficial

solution for improving the quality of health. This collaboration will resolve

the issue of data unavailability to the machine learning researcher.

Another major issue is, we need more so-phisticated techniques to deal

extensive amount of healthcare data, especially in future, when more of

the healthcare industry will be based on body senor network.

24 Muhammad Imran Razzak, Saeeda Naz and Ahmad Zaib

5.2 Need to Capitalize Big Image Data

Deep learning applications rely on extremely large dataset, however,

availabil-ity is of annotated data is not easily possible as compared to

other imaging area. It is very simple to annotate the real world data i.e.

annotation of men and woman in crowd, annotating of object in real world

image. However, annotation of medical data is expensive, tedious and time consuming as it requires extensive time for expert (especially due the

sensitivity of domain, annotation required opinions of different expert on

same data), furthermore annotation may not be always possible in case of

rare cases. Thus sharing the data resource with in different healthcare

service providers will help to overcome this issue somehow.

5.3 Advancement in Deep Learning Methods

Majority of deep learning methods focus on supervised deep learning how-

ever annotations of medical data especially image data is not always possible

i.e. in case when rare disease or unavailability of qualified expert. To over-

come, the issue of big data unavailability, the supervised deep learning field is

required to shift from supervised to unsupervised or semi-supervised. Thus,

how efficient will be unsupervised and semi-supervised approaches in medical

and how we can move from supervised to transform learning without effecting

the accuracy by keeping in the healthcare systems are very sensitive. Despite

current best efforts, deep learning theories have not yet provided complete

solutions and many questions are still unanswered, we see unlimited in the

opportunity to improve.

5.4 Black-Box and Its Acceptance by Health Professional

Health professional wary as many question are still unanswered and deep

learning theories has not provided complete solution. Unlike health profes-

sional, machine learning researchers argues interoperability is less of an issue

than a reality. Human does not care about all parameters and perform com-

plicated decision, it is just mater of human trust. Acceptance of deep learning

in health sector need proof form the other fields, medical expert, are hoping to

see its success on other critical area of real world life i.e. autonomous car,

robots etc. Even though great success of deep learning based method, decent

theory of deep learning algorithms is still missing. Embarrassment due to the

absence this is well recognized by the machine learning community. Black-

Deep Learning for Medical Imaging 25

box could be another one of the main challenge, legal implications of black box functionality could be barrier as healthcare expert would not rely on it. Who could be responsible if the result went wrong. Due to the sensitivity of this area, hospital may not comfortable with black-box i.e. how it could be traced that particular result is from the ophthalmologist. Unlocking of black box is big research issue, to deal with it, deep learning scientist are working toward unlocking this proverbial black box.

Fig. 11: Deep Learning: A Black Box

5.5 Privacy and league issues

Data privacy is effected by both sociological as well as technical issue,

that need to be addressed jointly from both sociological and technical

perspec-tives. HIPAA (Health Insurance Portability and Accountability Act

of 1996) comes to mind when privacy is discussed in health sector. It

provides legal rights to patients regarding their personally identifiable

information and es-tablish obligations for healthcare providers to protect

and restrict its use or disclosure. While the rise of healthcare data,

researchers see big challenges that how to anonymize the patient

information to prevent its use or disclosure ? The limited restriction data

access, unfortunately reduce information con-tent too that might be very

important. Furthermore, real data is not static but its size is increasing and

changing overtime, thus prevailing methods are not sufficient.

26 Muhammad Imran Razzak, Saeeda Naz and Ahmad Zaib

6 Conclusion

During the recent few years, deep learning has gained a central position

toward the automation of our daily life and delivered considerable improve-

ments as compared to traditional machine learning algorithms. Based on the

tremendous performance, most researchers believe that within next 15 years,

deep learning based applications will take over human and most of the daily

activities with be performed by autonomous machine. However, penetration of

deep learning in healthcare especially in medical image is quite slow as

compare to the other real world problems. In this chapter, we highlighted the

barriers, that are reducing the growth in health sector. In last section, we

highlighted state of the art applications of deep learning in medical image

analysis. Though, the list is by no means complete however it provides an

indication of the long-ranging deep learning impact in the medical imaging

industry today. Finally, we have highlighted the open research issues. Many big research organization are working on deep learning based

solu-tion that encourage to use deep learning to apply deep learning on

medical images. Looking to the brighter side of machine learning, we are

hoping the sooner human will be replaced in most of the medical

application especially diagnosis. However, we should not consider it as

only solution as there are sev-eral challenges that reduces its growth. One

of the big barrier is unavailability of annotated dataset. Thus, this question

is still answerable, that whether we will be able to get enough training data

without effecting the performance of deep learning algorithms. Recent

development on other application showed that bigger the data, better the

result, however, how big data could be used in healthcare. So far deep learning based application provided positive feedback,

however, but due to the sensitivity of healthcare data and challenges, we should look more sophisticated deep learning methods that can deal complex healthcare data efficiently. Lastly we conclude that there are unlimited opportunities to improve healthcare system.

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